There is a catalog about my new program, but I can't understand what these documents represent
You can find more information about the structure that create-react-app generates in its docs:
https://create-react-app.dev/docs/getting-started
If you search by file name...
serviceWorker: https://create-react-app.dev/docs/making-a-progressive-web-app/
setupTests: https://create-react-app.dev/docs/running-tests/#initializing-test-environment